Traffic accidents are the major public health problem of adolescents and young adults, accounting for 16,500 deaths yearly in this group. Assuming that traffic accidents are the manifestation of a disturbed equilibrium between the driver, his vehicle and his physical, psychological and social environment, we propose to study the relationships among these parameters using a multi-disciplined epidemiological approach. By interviewing in depth a large random sample of New England male drivers, age 16 - 25, which will adequately control for exposure to risk, we will carry out both a retrospective and prospective study which will (1) determine the prevalence as opposed to the reported incidence of accidents, and (2) identify those differences in family psychopathology, individual psycho-social functioning, peer-group affiliation,and current environmental stress which bear a causal relationship to accident rates.